Heat exchanger cores in common use today generally employ a set of tubes to carry the primary circulating fluid and a plurality of parallel fins or plates which fit over the tubes. This construction requires rather expensive tooling to make the fins, which have a large number of precisely located holes corresponding to the location of the tubes. The assembly of such units is not readily adapted to automated techniques so that substantial and costly manual assembly must take place. The present invention substantially reduces manufacturing costs and assembly time by completely eliminating the use of fins.
A separate consideration in the construction of heat exchangers is their ability to withstand extreme environmental conditions such as vibration, thermal cycling and pressure gradients. It is also toward meeting this combination of requirements which the present invention is directed.
Conventional heat exchanger cores are usually used in conjunction with some means for propelling the secondary fluid through the core. Typically the secondary fluid is air and the means for moving the air is a fan or blower. This movement causes heat to be transferred between the air and the heat exchanger core. Such fans or blowers must rotate at high speeds to cause the air to flow through the restricted flow paths of the heat exchanger. The result of these high rotational speeds is that substantial noise emanates from the fans. The present invention allows a favorable construction of the exchanger core to enclose the fan thereby reducing the noise considerably. This construction is effected without sacrificing thermal performance.
Another major difficulty with conventional heat exchangers is their inherently large volume. This is particularly so because of the necessary physical separation between the air mover (fan or blower) and the fin and tube core. The present invention, on the other hand, permits complete flexibility of configuration which can result in complete integration of the core and blower to maximize the use of available volume.